Search Results (267)

Sodium-cooled fast reactors (SFRs) are being developed with various fuel cycle strategies, including once-through and recycling options. Initial U.S. deployments are expected to use compact SFR cores fueled with high-assay low-enriched uranium (HALEU). As SFR technology advances, higher fuel burnups and lower enrichments are anticipated. This study provides an economic assessment of utilizing HALEU in SFRs with a once-through fuel cycle (OTC) compared to recycling used nuclear fuel (UNF) across a range of advanced fuel and reactor designs. As an alternative to current once-through options (FC #1), three recycling alternatives are evaluated: (FC #2) recovered uranium (RU) downblended for pressurized water reactor (PWR) fuel, (FC #3) RU re-enriched for SFR fuel, and (FC #4) RU co-recycled with transuranics (RU/TRU) for SFR fuel. Results indicate that recycling RU from SFR UNF in both fresh PWR and SFR fuel can be economically advantageous compared to the OTC approach, provided the U-235 content remains sufficiently high—a condition met by current and near-term SFR designs. Increased burnup and in situ plutonium production in SFRs reduce overall OTC costs and natural uranium requirements. However, the economic viability of recycling SFR RU depends strongly on the specific UNF composition and the recycling pathway chosen. Recycling both RU and TRU consistently offers the lowest fuel cycle costs across all scenarios, even as fuel and reactor designs advance. These findings provide a framework for identifying when recycling offers economic benefits over direct disposal, informing future fuel cycle decisions for advanced reactors. Full article

Photocatalysis is a promising route for the environmentally friendly destruction of organic pollutants and recycling the polluted water in industrial contexts for future environmental challenges. In this novel research work, the coupling of definite proportions of silver phosphate and g-C₃N₄ is carried out sonochemically for engineering S-scheme Ag₃PO₄/g-C₃N₄ heterojunctions. With the data obtained from a N₂-adsorption–desorption isotherm, a diffuse reflectance spectrum, X-ray diffraction, a high-resolution transmission electron microscope and zeta potential measurement, as-synthesized nanocomposites are fully characterized and defined. Successful coupling of Ag₃PO₄/g-C₃N₄ heterojunctions was verified given the existence of diffraction peaks of g-C₃N₄ and Ag₃PO₄; the shift in the peak position of the DRS spectrum of g-C₃N₄ from 440 to 463 nm; and the decrease of 68% in the photoluminescence emission peak. The crystalline size of the nanocomposite decreased from 76 to 25 nm, which was ascribed to coupling of Ag₃PO₄ on g-C₃N₄ under sonochemical conditions. The as-synthesized nanocomposites exhibited different trends in the destruction of rhodamine B dye. The experimental results indicated that the sample containing 15 weight % of Ag₃PO₄ degraded 89% of the RhB dye. Precise analysis of reactive radicals species experiments indicated that superoxide radicals and positive roles directed the charge transportation between g-C₃N₄ and Ag₃PO₄ semiconductors toward the S-scheme mechanism that produces charge radicals of auspicious redox efficiency. Full article

The growing demand for low-carbon building materials and the challenges of handling agroforestry waste and discarded EPS particles have spurred research toward developing novel building composites that utilize solid waste. Therefore, this study aims to develop a lightweight geopolymer composite incorporating these recycled materials to balance thermal insulation, mechanical strength, and waterproofing properties. In this work, geopolymer served as the binder, with various types of raw biomass (sawdust, rice husk, rice straw, and coconut fiber) as the primary aggregates and EPS particles as an additive to create a closed-pore structure. The microstructure of the raw biomass was characterized by SEM, while its specific surface area and average pore diameter were determined by BET analysis. Furthermore, the prepared composites were comprehensively evaluated in terms of their microstructure, pore structure (MIP), density, thermal conductivity, compressive strength, total water absorption, capillary water absorption, surface wettability, and UV aging behavior. The results showed that the prepared composites exhibited a porosity of 59.9–65.7%, a density of 492.9–586.3 kg/m³, a compressive strength of 7.3–10.9 MPa, a thermal conductivity of 0.115–0.142 W/(m·K), a total water absorption of 35.2–42.2%, capillary water uptake coefficients of 4.9–11 kg/m², and a water contact angle exceeding 140° (after modification). In addition, the developed composites offered significant environmental and economic benefits, with a low carbon footprint and an estimated cost of 100.6–150.3 USD/m³, making them more competitive compared to traditional insulation materials. Meanwhile, this study provides a scientific basis for developing high-strength building insulation materials from agroforestry waste, thus outlining a promising direction for future research and industry development. Full article

Improper disposal of coffee-processing by-products can cause environmental pollution, greenhouse gas emissions, and resource loss, whereas their reuse in coffee plantations may support sustainable production. This review systematically examines the material properties, stabilization methods, field application pathways, agronomic effects, quality responses, and environmental risks of coffee-pulp-type by-products in cultivation. Relevant studies published up to June 2026 were retrieved from Web of Science, Scopus, ScienceDirect, SpringerLink, Google Scholar, and CNKI and qualitatively synthesized along the soil–plant–quality continuum. Current evidence suggests that properly stabilized materials, applied at appropriate rates, can improve soil organic matter, structure, water and nutrient retention, microbial activity, plant growth, photosynthesis, and crop yield in plantations. They may also indirectly influence green bean quality by regulating sugars, amino acids, chlorogenic acids, and caffeine. However, these effects depend strongly on material properties, maturity, application rate, coffee genotype, soil and climatic conditions, and management practices. Excessive or insufficiently decomposed materials may cause soil acidification, phytotoxicity, oxygen depletion, nutrient imbalance, and yield–quality trade-offs. Overall, recycling within plantations can turn processing waste into farm inputs, reinforce on-farm carbon and nutrient cycles, ease disposal burdens, and advance BCG and wider circular-economy principles in practice. Full article

This study presents a screening-level conceptual, stoichiometric, and scenario assessment of a pathway linking sulfur dioxide (SO₂) capture from coal-fired flue gas to sulfuric acid production and the downstream reaction of sulfuric acid with pretreated scrap aluminum. A regenerable sodium sulfite (Wellman–Lord) capture route, followed by gas polishing and drying, catalytic SO₂ oxidation, controlled SO₃ absorption, acid conditioning, and an Al–H₂SO₄ reactor, is used as the reference configuration. The sulfur balance distinguishes sulfur in coal, ash retention, gaseous SO_x, SO₃/acid mist, absorber inlet and stack slip, captured sulfur, regenerated sulfur, and sulfate purge. Under the central assumptions, 1 t of sulfur in coal yields 0.849 t of recovered sulfur equivalent, 2.599 t of H₂SO₄, 0.477 t of aluminum feed, 2.419 t of anhydrous-equivalent Al₂(SO₄)₃, 4.240 t of commercial aluminum sulfate on a 17 wt% Al₂O₃ basis, and 42.4 kg of H₂ at 80% aluminum conversion. The upstream base-energy screen is 3.3–7.2 GJth and 0.18–0.45 MWhe per tonne of sulfur in coal. Diluting the acid to the selected 0.5–1.0 M aluminum-reaction window and subsequently producing a 17 wt% Al₂O₃ product creates a minimum water-removal load of 21.6–47.6 t and a latent-heat floor of approximately 49–108 GJth/t S. Retail prices are replaced by 2024 customs unit values, and internal-acid-production and sulfuric-acid-opportunity-cost boundaries are evaluated separately. In the central opportunity-cost case, the H₂ value must reach approximately 6.9 USD/kg merely to balance material values before CAPEX, OPEX, energy, purification, transport, and environmental-compliance costs. The Afşin–Elbistan A case is treated as a full-design-throughput illustration based on an historical 18 Mt/y coal requirement, not as a measured current operating average; coal sulfur is tested over 1.0–2.5 wt%. The aluminum step is restricted to cooled and diluted 0.5–1.0 M H₂SO₄ at 40–60 °C, and direct H₂ production from 96 to 98 wt% acid is not assumed. Plant-specific capacity factor, time-matched coal assays, flue-gas flow, oxygen-corrected stack data, reaction kinetics, gas purity, and product quality remain to be verified. The integrated sustainability screening indicates conditional circular-economy potential rather than a demonstrated sustainability advantage: sulfur recovery must be weighed against energy and water demand, sulfate purge and wastewater, diversion of recyclable aluminum from remelting, hydrogen purification, and market-scale product offtake. The pathway therefore remains a research hypothesis requiring experimental validation, process simulation, techno-economic assessment, comparative life-cycle assessment, safety analysis, and market verification. Full article

Rapid urbanization has intensified two critical urban challenges: the urban heat island effect and stormwater runoff. This study evaluates the pilot-level field performance of a low-tortuosity permeable pavement (LTPP) system in potentially contributing to improved thermal regulation and hydraulic functionality. The system comprises a reduced-tortuosity upper block incorporated with bottom ash (BA) as a recycled fine aggregate and an underlying storage unit connected through an interlocking configuration, enabling direct infiltration while reducing clogging susceptibility and improving resistance to settlement and displacement. Field tests included thermal imaging, water-spraying infiltration-storage and vehicle-loading observations, and theoretical storage analysis. Initially, conventional permeable pavement (PP) dry surface temperature was measured at 44.2 °C, whereas the LTPP system already exhibited a lower temperature of 42.4 °C. During the evaporative stage after wetting, the LTPP system showed a lower temperature recovery rate, with a 2.91% increase between 90 and 120 min compared with 3.60% for conventional permeable pavement, indicating improved surface-temperature regulation. The storage calculations approximated that the LTPP system could theoretically buffer the simulated 15.63 mm/h rainfall by 6.65 to 7.32 h. It was also determined using historical rainfall data that the LTPP system, especially when provided with an outlet or drainage system, could effectively accommodate short- to medium-duration rainfall. Water-spraying tests confirmed rapid infiltration and subsurface storage, while vehicle-loading observations showed no noticeable displacement or settlement. These findings highlight the potential of a multifunctional permeable pavement design strategy that combines low-tortuosity flow paths, functional recycled aggregate selection, and subsurface storage for surface-temperature regulation and stormwater management. Full article

To address the inherent drawbacks of peroxymonosulfate advanced oxidation processes (PMS-AOPs), including the low efficiency of reactive species production, short radical half-lives, and restricted pollutant degradation performance, sodium salt-assisted modification was adopted to fabricate ZIF-8-derived carbon. In this study, sodium salt-assisted modification was adopted to treat ZIF-8, and the chlorine-doped derived carbon materials HNC-T_x-Cl were prepared for peroxymonosulfate activation and tetracycline degradation in water. Compared with NC-800 fabricated by direct calcination of ZIF-8 at 800 °C, HNC-800-Cl synthesized via NaCl-assisted calcination exhibits more abundant pore structures and richer carbon defects, with a specific surface area of 1115 m²/g and a high graphitic defect ratio I_D/I_G of 1.20. Catalytic tests reveal that HNC-800-Cl achieves 93.39% tetracycline removal within 90 min at a catalyst dosage of 0.05 g L⁻¹ and PMS concentration of 0.1 mM. The system possesses a strong anti-interference ability toward complex water environments, maintaining a favorable degradation performance in the presence of coexisting anions, natural organic matter and actual water matrices. It also exhibits outstanding cycling stability, retaining a removal rate of 80.34% after five recycling runs. Radical quenching experiments and EPR characterization verify that superoxide radical (·O₂⁻) is the dominant reactive species during tetracycline degradation. Both the radical and non-radical pathways are clarified to illustrate the mechanisms of PMS activation and pollutant degradation. This work provides a novel catalytic material strategy to overcome the deficiencies of conventional PMS-AOPs, and offers a new perspective for structural regulation and non-metallic doping modification of ZIF-8-derived carbon materials. Full article

Concerns have increased significantly in recent years due to the presence of microplastics in different environmental compartments given that this pollutant can cause adverse effects on the environment and human health. The present review integrates representative studies of Mexican researchers proposing solutions to these concerns, addressing ecological risk and the human food chain, microplastic ingestion by animals, water and sediment pollution, physical/chemical methods for microplastic removal from water, and chemical recycling as a research direction in plastic waste management. Several publications from Mexican institutions are limited to the occurrence and identification of polymers, and a smaller number of documents are focused on solutions to microplastic pollution. Fibers, fragments, spheres, films, and foams have been found in aquatic compartments, sediment, and animals. High ecological risk has been documented in some aquatic compartments. There is a lack of standardized protocols for sampling, extraction, identification, and reporting. Flocculation is a cost-effective approach and may be one of the most promising options for removing microplastics from fresh water. Bioremediation using microorganisms and chemical recycling appear to be the two most widely considered approaches to reverse plastic pollution. National databases, permissible limits, and mandatory monitoring programs should be developed, as these are essential components of an effective regulatory framework. Full article

This work reports the development of innovative enzyme–titanium nanobiohybrids synthesized via a protein-assisted approach to obtain efficient and sustainable photocatalysts for environmental remediation. By addressing the limitations of conventional TiO₂ nanoparticle synthesis, this strategy enables controlled material properties under milder, potentially scalable conditions for enhanced ROS-driven degradation of persistent dye pollutants. This work employs a bio-assisted synthesis approach using β-glucosidase as a protein scaffold, TiCl₄ as the titanium precursor, and H₂O₂ in bicarbonate buffer at room temperature, eliminating the need for harsh conditions and high temperatures. The biological moiety guides the nanoparticle formation, controlling size and morphology while preventing aggregation, all performed under mild conditions. X-ray diffraction determined that the Ti hybrid was composed of TiO₂ brookite species. TEM analyses demonstrated the formation of well-dispersed nanostructures of around 700 nm. The resulting nanobiohybrids showed excellent photocatalytic activity, achieving >99% Rhodamine B degradation under UV light in only 1 h compared to visible light. The catalyst was capable of degrading Rhodamine B at a concentration approximately 36 times above the recommended threshold for water. Furthermore, a preactivation of the catalyst by direct exposition of it to UV-395 nm light greatly enhanced the efficiency in the photocatalytic process, being inactive in visible light. The Ti–enzyme hybrid showed excellent recyclability over five consecutive cycles and retained good activity after storage, demonstrating its stability. This study introduces a sustainable and efficient route for synthesizing Ti-based nanobiohybrids, providing a promising strategy for advanced photocatalytic applications in water treatment and environmental remediation. Full article

Cement manufacturing is a major source of carbon dioxide (CO₂) emissions globally. Cement replacement materials are increasingly used to minimize the environmental impact of concrete production. In the present study, the mechanical and environmental performance of concrete mixtures containing fly ash and recycled glass powder as partial cement replacements at levels of 10%, 20%, and 30% were investigated. Workability, unit weight, compressive strength, and water permeability tests were conducted to evaluate the effects of replacements on concrete behavior. Carbon emissions decreased as the substitution ratio increased, with the highest reduction (28.9%) observed in the mixture containing 30% fly ash. Compressive strength values ranged from 21.9 to 27.0 MPa, indicating that all mixtures fell within the intended strength range. Two types of cement replacements—fly ash (FA) and recycled glass powder (GP)—were evaluated separately. Compared to GP mixtures, FA mixtures generally exhibited lower permeability (up to 50%) and better strength retention (up to 9.6 percentage points), though both materials contributed to reducing embodied carbon. The mixture containing 30% fly ash demonstrated the highest environmental efficiency, with a carbon intensity of 10.84 kg CO₂/MPa, corresponding to a 19.2% reduction compared with the control. For recycled glass powder, the 20% replacement level offered the most balanced performance, while higher replacement ratios led to more pronounced strength losses. This study provides a direct comparison of FA and GP under identical mixture conditions using performance-normalized environmental indicators. The results indicate that, under the tested conditions, fly ash exhibits a better combination of carbon emission reduction and mechanical strength than recycled glass powder. Full article

Viscosity reducers are essential additives for water-based drilling fluids (WBDFs), serving to counteract the rheological degradation induced by the high-temperature and high-salinity conditions commonly encountered in deep and ultra-deep well drilling. This paper systematically reviews the research progress in this field, categorizing viscosity reducers into three major systems: modified natural materials, industrial waste utilization, and synthetic polymers. Modified natural material viscosity reducers, derived from renewable materials such as lignin and humic acid via chemical modification, are environmentally friendly products. The preparation of viscosity reducers from industrial wastes realizes both resource recycling and economic benefits. Synthetic polymer viscosity reducers, incorporated with functional monomers such as sulfonic and carboxylic groups, achieve high performance with temperature resistance exceeding 220 °C as well as excellent salt and calcium tolerance via rational molecular design, and represent the current mainstream research direction in the field. This paper provides an in-depth analysis of the action mechanisms of various viscosity reducers, summarizes the performance characteristics, synthesis methods and application status, and identifies challenges in structure–property relationship elucidation, extreme working condition adaptability, and technology transfer efficiency. Finally, future development trends are discussed, with emphasis on precision molecular design, ultimate performance requirements for ultra-deep wells, environmentally sustainable approaches, and the establishment of standardized evaluation protocols. This review aims to provide both theoretical insights and practical guidance to support the efficient development of deep oil and gas resources. Full article

The particular microstructure of hot-deformed Nd-Fe-B magnets leads to difficulties in finding a direct recycling route. In this work, a combination of field-assisted sintering technology/spark plasma sintering (FAST/SPS) and spark plasma texturing (SPT) is used as pre-compaction and deformation techniques, respectively, for the consolidation of crushed, hot-deformed Nd-Fe-B scrap. Field-assisted sintering has the unique advantage of maintaining fine microstructures during material densification, making it an ideal candidate for direct recycling of this material. Recycled magnets, made from 100 wt% crushed magnet scrap, were able to achieve energy products of over 200 kJ m⁻³ after FAST/SPS pre-compaction and SPT deformation. These recycled magnets could then be smoothed and cut to the size of industrial bar magnets for testing in the motor of a water pump. When tested, the recycled magnets could achieve 95% of the electromotive force compared to industrial standard magnets. Full article

Waste lubricating oils (WLOs) represent a major stream of hazardous petroleum-based residues, with global generation exceeding 24 million tons annually. Improper disposal of WLOs poses risks to soil, water, and air quality, while their chemical composition makes them a potential secondary resource within circular economy frameworks. This review summarizes conventional, advanced, and emerging technologies reported for the recycling and valorization of WLOs into high-value petrochemicals and carbon-based materials. Established processes such as acid–clay treatment, solvent extraction, and vacuum distillation are discussed together with more recent approaches, including catalytic upgrading, hydrotreatment, membrane separation, and thermochemical conversion methods such as pyrolysis and catalytic cracking. Reported data on process performance, environmental considerations, techno-economic indicators, and life cycle assessment outcomes are comparatively analyzed to outline current trends, technical challenges, and future development directions in WLO recycling. Particular attention is given to thermochemical pathways capable of generating carbonaceous materials, including carbon black, porous carbons, and functional carbon nanostructures with potential applications in adsorption, catalysis, electrochemical systems, and tribological formulations. Hybrid and integrated process configurations described in the literature are highlighted for their potential to improve recovery efficiency, enhance product quality, and reduce environmental burdens. In addition, recent life cycle assessment (LCA) and techno-economic analysis (TEA) studies are reviewed to provide insight into the environmental and economic implications of advanced re-refining systems. Overall, the reviewed literature indicates that WLO recycling represents not only an important element of sustainable lubricant management but also a promising waste-to-carbon strategy for the production of value-added carbon-based materials and petrochemical products. Full article

Lithium has become one of the key raw materials for the energy transition due to the central role of lithium-ion batteries in electromobility, energy storage, and the integration of renewable energy sources. However, the rapid increase in demand reveals growing environmental, social, geopolitical, and market tensions. The aim of the paper is a critical synthesis of global lithium utilization from the perspective of challenges, technological innovations, and integrative strategies supporting a more sustainable material-energy system. A broad, systematic literature review covering the entire value chain was applied: resources, extraction, processing, end-use applications, second life of batteries, recycling, and governance. The analysis shows that the strategic importance of lithium arises from the increasing demand pressure from electric vehicles and stationary storage, while the sustainability of the current model is constrained by supply concentration, uneven control over downstream stages, the water-carbon footprint of extraction and processing, social conflicts, and incomplete integration of secondary loops. At the same time, innovations such as direct lithium extraction (DLE), recovery from geothermal brines, design for recycling, second life, and battery passports can partially alleviate these tensions, but they do not eliminate the need for primary supply in the short term. The conclusion of the work is that sustainable global lithium utilization requires simultaneous diversification of sources, development of circular value chains, and multi-level governance integrating resource security, environmental efficiency, and social legitimacy. Full article

Microplastics (MPs, plastic particles < 5 mm) and nanoplastics (NPs, plastic particles generally <1 µm), collectively referred to as micro/nanoplastics (MNPs), have emerged as critical contaminants in wastewater systems due to their persistence, small size, and ability to act as vectors for co-contaminants. Conventional wastewater treatment technologies are often insufficient for the effective removal of microplastics, particularly for smaller particles and nanoplastics, necessitating the development of functional materials and innovative treatment strategies. In this review, recent advances in carbon-based materials, cellulose-based materials, and their hybrid carbon–cellulose composites for microplastics removal are critically analyzed and comparatively discussed. Particular attention is given to the structure–function relationships governing adsorption performance, including the roles of hierarchical porosity, surface chemistry, and interfacial interactions. The key mechanisms responsible for microplastics capture—such as hydrophobic interactions, π–π stacking, hydrogen bonding, electrostatic attraction, physical entrapment, and pore trapping—are systematically discussed. Carbon–cellulose composite materials are highlighted as a promising class of multifunctional adsorbents due to their synergistic combination of hydrophilic cellulose scaffolds and hydrophobic carbon domains. This dual functionality enables efficient removal of microplastics across a wide range of sizes and morphologies. Recent developments in magnetic and superhydrophobic composite systems further demonstrate enhanced separation efficiency, recyclability, and potential applicability in real wastewater environments. In addition to summarizing recent progress, this review critically examines the methodological inconsistencies, mechanistic uncertainties, and practical limitations associated with current adsorption systems. Despite significant progress, several challenges remain, including the lack of standardized evaluation methods, limited validation under real wastewater conditions, material stability issues, and scalability constraints. Future research directions are proposed, focusing on rational material design, sustainable carbon sources, multifunctional hybrid systems, and integration into existing treatment infrastructures. The development of sustainable hybrid adsorption systems for microplastics remediation also contributes to the achievement of Sustainable Development Goal 6 (Clean Water and Sanitation) by supporting improved wastewater treatment technologies and reduction in emerging aquatic contaminants. Full article